title: Bioassay-directed fractionation and sub-fractionation for mutagenicity and chemical analysis of diesel exhaust particles.
abstract: Several types of diesel exhaust particles (DEPs) have been used for toxicology studies, including a high-organic automobile DEP (A-DEP) from Japan, and a low-organic forklift DEP developed by the National Institute of Standards and Technology (N-DEP). However, these DEPs were not characterized extensively for chemical composition or sub-fractionated and tested extensively for mutagenicity. We collected a compressor-generated DEP (C-DEP) and characterized it by conducting bioassay-directed fractionation of the extractable organics in Salmonella and correlating the results by hierarchical clustering with the concentrations of 32 polycyclic aromatic hydrocarbons (PAHs). Relative to A- and N-DEP, the mutagenic potency of C-DEP was intermediate in TA100 +S9 (PAH mutagenicity) but was lowest in TA98 -S9 (nitroarene mutagenicity). More than 50% of the mass of the extractable organics of C-DEP eluted in the nonpolar Fraction 1, and only ∼20% eluted in the moderately polar Fractions 2 and 3. However, most of the mutagenicity eluted in Fractions 2 and 3, similar to A-DEP but different from N-DEP. HPLC-derived mutagrams of 62 sub-fractions per fraction confirmed that most of the mutagenicity was due to moderately polar compounds. The diagnostic strains identified a strong role for PAHs, nitroarenes, aromatic amines, and oxy-PAHs in the mutagenicity of C-DEP. Hierarchical clustering confirmed the importance of oxy-PAHs but not that of nitroarenes. To our knowledge this is the first use of hierarchical clustering to correlate chemical composition with the mutagenicity of a complex mixture. The chemical analysis and mutagenicity of C-DEP described here makes C-DEP suitable for additional toxicological studies.
authors.affiliation: National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina; Center for Environmental Medicine, Asthma and Lung Biology, University of North Carolina, Chapel Hill, North Carolina.
authors.forename: Esra
authors.initials: E
authors.lastname: Mutlu
authors.forename: Sarah H
authors.initials: SH
authors.lastname: Warren
authors.forename: Peggy P
authors.initials: PP
authors.lastname: Matthews
authors.forename: Charly
authors.initials: C
authors.lastname: King
authors.forename: William P
authors.initials: WP
authors.lastname: Linak
authors.forename: Ingeborg M
authors.initials: IM
authors.lastname: Kooter
authors.forename: Judith E
authors.initials: JE
authors.lastname: Schmid
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Ross
authors.forename: M Ian
authors.initials: MI
authors.lastname: Gilmour
authors.forename: David M
authors.initials: DM
authors.lastname: Demarini
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001681:Biological Assay; D005591:Chemical Fractionation; D002851:Chromatography, High Pressure Liquid; D008401:Gas Chromatography-Mass Spectrometry; D009152:Mutagenicity Tests; D009153:Mutagens / Q000032:analysis*; D052638:Particulate Matter / Q000633:toxicity; D011084:Polycyclic Aromatic Hydrocarbons / Q000633:toxicity*; D012486:Salmonella typhimurium / Q000187:drug effects*; D001335:Vehicle Emissions / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D009153:Mutagens; D052638:Particulate Matter; D011084:Polycyclic Aromatic Hydrocarbons; D001335:Vehicle Emissions
keywords: Salmonella; combustion emissions; complex mixtures